Dishwashing apparatus provided with centrifugal separation sump



Nov. 3, 1953 F. A. WALKER 2,657,695

DISHWASHING APPARATUS PROVIDED WITH csmamucm. SEPARATION SUMP Filed Aug. 24, 1946 2 Sheets-Sheet 1 Fig.1. f

Inventor-z Forrest A. Walker,

-' b Hi Atoor-neg.

Nov. 3, 1953 F. A. WALKER 2,657,695

DISHWASHING APPARATUS PROVIDED WITH CEINTRIFUGAL SEPARATION SUMP Fi led Aug. 24, 1946 Z'Sheets-Sheet 2 115 e nb 01* Fo'T-r'esc A. Wal ker,

H is Attorneg.

Patented Nov. 3, 19153 UNITED STATES PATENT OFFICE DISHWASHING' APPARATUS PROVIDED WITH GENTBIFUGAL- SEPARATION- SUMP Forrest A. Walker, Wheaten, 111., assignor to General Electric" Company, a. corporation. of

New-York AppIicatfonAu'gustZ4, 1946, SeriaINO.-692,.8I3f

(Cl. 134-11I);

2= Claiins. 1.

This invention relates to dishw'ashi'ng apparatus; more particularly to such apparatusprovided' with a washing vat having therein a power driven impeller which hurls the washing water upwardly and outwardly in the vat to effect the'washing of the dishes supported in the Vat; and it has for its object theprovision of improvements in such. apparatus which effect the separation of food soils from the washingwater'so' as to prevent the recirculation thereof by the, impeller-as it recirculatesthe water;

For a more complete'understanding' of this invention, reference should be; had to the accompanying drawings in which Fig. I is a. vertical elevation ofdishwashing apparatus embodying this invention, parts being broken away and shown in section so as to illustrate certain structural details; Fig. 2 is a vertical sectionsl view taken through a portion of the apparatus shown in Fig; 1, this figure, however, being drawn to a V materially larger scale than is Fig. 1; andFig. 3 is a somewhat diagrammatic perspective View drawn to a smaller scale than Figs. I and 2' and illustrating certain elements of the washing, apparatus.

Referring to the drawings, this invention hasv been shown in one form as app-lied to dishwashing apparatus which comprises a vat I mounted in a cabinet 2'. Ihe vat I isformed of'a pair of vertical sidewalls 3, a vertical rear wall 8; a generally horizontal top wall 5, and a bottom wall 6, these walls being joined integrally together so as to provide a' vat which is closed; except. atv the front where an opening 6a is provided. This opening normally is closed by means of a vertical door 7 which hinges at the bottom so thatit may be swung downwardly from its" closed position to anopen position. The two vertical side walls 3; the" vertical rear wall 6, and the vertical" door. T when closed form an upright vat which is substantially square in horizontal cross section.

The'bottom wall 6, as shown is depressed, this wall being formed by four downwardly-inclinedv roughly triangular sections 8 (shown most clearly in Fig. 3) and which have their edges integrally joined and which terminate in a relatively deep depressed section 9 at the central: partof: the bottomwall 6. This section 9: is defined. by an outer generally vertical circular wall H) which inclines. inwardly as it leaves.- the wall sections 8 and; approaches the bottom,v as. clearly shown inFig-s; 2 and 3. Section 9' further comprises a reentrant centralw-all part. l l,, generally oi 'conical'a shape,

joins the circular outer wall it and the reentrant wall I.

Mounted" in the depressed bottom wall 6 of the vat is a water circulating impeller 13- rotatable on a vertical axis'which is substantially coincident with the central Vertical axis of the vat. Preferably' and as shown, this impeller is constructedand arranged as that disclosed in the copending application of Nobel-H. Koertge, Serial No; 426,889; filed January 15', 1942', now Patent No. 2,422,022, dated June 10', 1947, and which application is assigned to' the assigneeof the instant application. Briefly, this impeller comprises an apron-like hub M from which aparrot water circulating blades i5 extend outwardly; the two blades being positioned opposite each other on the apron, as most clearly shown in Fig. 3. Each blade has. a water engaging face It curving downwardly and forwardly from the blades upper edge to its lower edge in the direction of rotation of the impeller, which direction is: counter-clockwise as viewed in Fig. 3; Also, mounted on the apron are air; fan blades l'l'.

The impeller is mounted upon and driven by a drive shaft l8 which in turn is driven by means of a suitable electric motor is located under the bottom wall 6, as shown, the shaft is entering the bottom wall through acylinder 28 extending up from this wall, as shown, and which has its lower end sealed to it.

Washing water is fed to the vat it through a spray device 21. mounted on the upper wall 5 of the vat and" to which water is fed through. a supplyconduit 22, the fiow'of water through this; conduit being controlled by a suitable inlet valve 23;

Water is withdrawn from the vat l to a drain pipe' 24 through a suitable drain valve structure 25 which preferably and as shown will be arranged as are the drain val'vesdescribed and claimed in the U. S'. Patents Nos; 2,271,993 to S. Stoddard, February 3, 1942, and 2339306 to F. A. Walker, January 18, 1944. Briefly, this valve structure comprises a tubular discharge port section 25 controlled by a valve 2 1, as shownin the Walker patent. The operation ofthis valve is controlled by a' control lever 23- and this lever is operated by a magnet 29, as in the Stoddard patent.

Suitable open-work sliding trays ac and 31 are mounted in the vat above the impeller It so that they may be slid out of and returned to the vat when the door. T is open for the purpose of load-- ing and unloading the dishes. The sliding rack construction may andpreferably Will be'of the and also a urv d bottom: Wa pa i h h type'described and claimed the Uni-ted States 3 Patent No. 2,290,653 to E. S. Stoddard, dated July 21, 1942.

When the proper quantity of water is supplied to the vat and allowed to collect therein by having the drain valve closed, and the motor is then energized to drive the impeller IS, the two impeller blades l5 engage the pool of water in the bottom of the vat and hurl it upwardly and outwardly in the vat through the two racks 3B and Si, as indicated in Figs. 2 and 3 by the arrows 32 and 33 directed upwardly and outwardly. As the water is so hurled it also is generally rotated in the vat by the action of the rotating impeller blades in the direction of rotation of the impeller and about the vertical axis of rotation of the impeller. also, the water which is so hurled upwardly and outwardly ultimately engages the vertical walls 3, d and l of the vat and flows both forwardly and downwardly along these walls to return to the impeller for recirculation, as indicated by the arrows 3 (Fig. 3). That is, the upward and outward fiow of the water from the impeller and its flow back to the impeller is through a generally curved path which first goes up and out from the impeller and thence back downwardly and forwardly along the vertical walls of the vat to return to the impeller, see arrows 33 and Ta l in Fig. 3. This water which falls back to the impeller is recirculated thereby.

The features of this invention reside in the arrange; ent of the bottom wall 5, and the provision of a circular screen or perforated barrier 36 around the impeller and inside of the drain valve for preventing the recirculation of solid food particle which are washed off of the dishes by the upward and outward flow of the water and which are carried down to the bottom of the vat by the water as it returns for recirculation.

The barrier 38 is located down in the depressed section Q of the bottom wall around the impeller, inside of the drain valve opening as shown. It has a diameter only somewhat larger than the circular path swept by the outer edges of the impeller blades, and as shown it rests upon the conical reentrant wall part ll of the depressed section The height of the barrier is such that its upper end is about at the level of the free liquid level of the proper quantity of washing Water supp ied, which level is indicated by the line 36a Fig. l, and in the particular example illustrated the barrier is made of sheet stock perforated 'ith nine hundred and fifty-two holes per square inch, each having a diameter of .020 inch. i'his provides a open area in the barrier.

The circular barrier has its central vertical axis substantially coincident with the central vertical axis of the vat, and with the axi of rotation or the impeller. It is prevented from slipping side its from this position by a wire ring which in turn is centered by a plurality of radial wires 36c. ends attached to a plate 36d, which is fitted over the tube as shown. A flange 36s is fixed to the tube and bears on the plate 33d and the entire assembly is clamped to the bottom wall of the vat by a nut threaded on the lower proecting end of the tube, as shown.

In the structure of the section 9, the upwardly and outwardly directed wall part I ll, the upwardl and inwardly dir cted wall part i l and the connecting curved wall part 52 may be conveniently termed first, second and third Wall elements, respectively; whereby the lowermost portion of the annular ump thus definedis disposed These wires have their inner 4 below the lower edge of the blades it": of the impeller l3 and exteriorly of the sweep thereof.

The first operation of the machine is to separate by centrifugal action the food soil particles from the water before it is recirculated. This is accomplished by the depressed section 9 which in. effect i a circular centrifugal separation sump or chamber.

As the impeller blades operate to hurl water upwardly and outwardly in the vat they also operate to push the mass of water in the sump forwardly in the direction of rotation of the impeller. This mass rotates in the sump both within and without the barrier 36, as indicated by arrows 37 and 38 in Fig. 3. The return flow oi the water downwardly and forwardly of the vats upright walls, as indicated by the arrows 3d, accelerates or assists in rotating the water mass in the sump, as will be evident from Fig. 3. As this mass rotates, the food soil particles carried down into the Vat by the down flow of water are forced outwardl by centrifugal action away from the impeller and toward the outside wall of the sump, as indicated by numeral 39 in Fig. 2. However, this action is somewhat 0pposed by the return down flow of water, indicated by arrows in Fig. 3 and by arrows lll in Fig. 2. These downwardly flowing streams of water contact the rotating mass in the sump, and tend to move in radially across it. This causes turbulence and tends to rotate the food particles in a circular path lying in a vertical plane, as shown in Fig. 2. This action is greatly accentuated at the corner of the vat where the forward motion of the flowing water stream is substantially stopped and the stream is directed radially into the sump water mass, a indicated by arrows ti in Fig. 3.

In addition, unbalance in the loading of plates in the lower rack 36 accentuates the turbulent condition.

The perforated barrier 36 not only tends to reduce the eil'ects of turbulence, but it intercepts any of the food particles which tend to move into the impeller, and thereby functions to hold the food soil in the sump space between the barrier and the outer sump wall 5 t.

The cross flow of the vat soil particles due to the turbulent conditions dcscdbed above apparently is relatively gentle since the food particles are not driven violently into the perforations of the barrier. This is evidenced by the ease with which the food particles are stopped by the barrier and are flushed from it when the vat is drained.

Also, there is some opposition to the cross flow created by the impeller which when operating creates a slight water pressure outwardly in the direction of the barrier. This back pressure so to speak tends to drive food soil on the barrier outwardly away from it.

The vat is drained, of course, by opening the drain valve El. The location of this drain valve in the vertical side wall ill is a very important feature, since when the valve 2? is opened the segregated suspension of food soil in the bottom and outer parts of the sump 9 drain out first ahead of the bulk of the waste water. The subsequent passage of the remainder of the relatively clear waste water flushes the sump and also the barrier so as to carry away from it any of the food soil which has adhered to it during the washing operation of the machine.

It is the coaction of the separation sump and the barrier which effectively prevents the recirculation of food soil particles. It the separation sump were eliminated and the screen barrier only used, the barrier, if it were perforated with openings sufliciently small to screen food soil efiiciently, quickly would become clogged by food particles which would be forcibly driven into its apertures, and as a result it would dam up the water and prevent it from flowing to the impeller. Moreover, it could not possibly be selfcleaning, as here, by the subsequent drainage of waste liquid from the vat.

Furthermore, the separation sump should not be used without the barrier, because if it were, the water would have to be whirled at such a high velocity to eifect a complete separation that it would move the particles outwardly with such force that they would cake or crust on outer walls of the sump. The removal of this crust would require a tedious hand operation or some sort of a complex mechanical device.

By providing both the sump and the barrier, the water may be whirled in the sump at such a velocity that substantially all of the particles will tend to move toward the outer wall H] but they will not be forced into contact with it so that they will adhere to it in crust form. The barrier, however, confines the particles into the sump and prevents movement of them into the impeller.

While I have-shown and described a particular embodiment of my invention, it will be obvious to those skilled in the art that various changes and modifications may be made without departing from my invention in its broader aspects and I therefore aim in the appended claims to cover all such changes and modifications as fall within the true spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. Dishwashing apparatus comprising a vat having four upright side walls defining a washing chamber substantially rectangular in horizontal cross-section, and also having a depressed bottom wall, an impeller rotating in the depressed bottom Wall on an axis substantially coinciding with the central vertical axis of said chamber, said impeller having blades which engage cleansing liquid in said bottom wall so as to hurl it upwardly and outwardly toward said side walls and with a general rotary motion about said axis, said bottom wall having a still deeper depressed section at the center thereof, said section including an upwardly and outwardly directed first wall element and an upwardly and inwardly directed second wall element and a connecting curved third wall element cooperating to define an annular sump surrounding said impeller, the lowermost portion of said sump being located below said impeller and exteriorly of the sweep thereof, an upstanding cylindrical screen surrounding said impeller at the inner portion of said sump to prevent the passage of food particles with the liquid into said impeller, said impeller rotating the liquid in said sump so that said sump constitutes a centrifugal separation space causing the food particles suspended in the rotating liquid by the action of centrifugal force to move outwardly therein away from said screen toward said first wall element, said bottom wall arranged above said section directing the liquid returning by gravity from said side walls back into the upper portion of said sump and inwardly toward said screen causing turbulence in the rotating liquid in said sump to settle out the suspended food particles into said lowermost portion of said sump, said first wall element having a drain port formed therein adjacent to said lowermost portion of said sump, and a valve controlling said drain port.

2. Dishwashing apparatus comprising a vat having four upright side walls defining a washing chamber substantially rectangular in horizontal cross-section, and also having a depressed bottom wall, an impeller rotating in the depressed bottom wall on an axis substantially coinciding with the central vertical axis of said chamber, said impeller having blades which engage cleansing liquid in said bottom wall so as to hurl it upwardly and outwardly toward said side walls and with a general rotary motion about said axis, said bottom wall having a. still deeper depressed section at the center thereof, said section including an upwardly and outwardly directed first wall element and an upwardly and inwardly directed second wall element and a connecting curved third wall element cooperating to define an annular sump surrounding said impeller, the lowermost portion of said sump being located below said impeller and exteriorly of the sweep thereof, an upstanding cylindrical screen surrounding said impeller and having a diameter slightly larger than the sweep of said impeller and resting upon said second wall element substantially at the junction thereof with said third wall element to prevent the passage of food particles with the liquid into said impeller, said impeller rotating the liquid in said sump so that said sump constitutes a centrifugal separation space causing the food particles suspended in the rotating liquid by the action of centrifugal force to move outwardly therein away from said screen toward said first wall element, said bottom wall arranged above said section directing the liquid returning by gravity from said side walls back into the upper portion of said sump and inwardly toward said screen causing turbulence in the rotating liquid in said sump to settle out the suspended food particles into said lowermost portion of said sump, said first wall element having a drain port formed therein adjacent to said lowermost portion of said sump, and a valve controlling said drain port.

FORREST A. WALKER.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,014,509 0rd Jan. 9, 1912 1,123,260 Dusseau Jan. 5, 1915 1,382,117 O-pocensky June 21, 1921 1,445,320 Johnson Feb. 13, 1923 1,771,524 Brotz -1 July 29, 1930 2,003,003 Marbury May 28, 1935 2,044,132 Stoddard June 16, 1936 2,287,628 McMahan June 23, 1942 2,418,366 Powers Apr. 1, 1947 2,468,584 Wotring Apr. 26, 1949 

